Designer’s glossary: Swingy (effects)
Swingy also swinginess
/ ˈswɪŋi /
adjective
A swingy effect is any effect whose power varies wildly depending on some factors (e.g. current state of the game board or resources, number of players etc.) With swingy effects, the power levels for the best case and the worst case are too far apart, and because of that, the effect itself is generally difficult to evaluate, plan around and play around. Swinginess can generally be reduced by either lowering the best case power or increasing the worst case power. With both of these methods, the important thing is to change the balance in controllable increments, since it’s easy to potentially start increasing the swinginess by going too far in either direction.
Antonym: consistent
Swinginess is more often than not tied to randomness, specifically output randomness. If the ‘floor’ and ‘ceiling’ of an effect depend on some factor that the player has little to no control over, the final outcome of the effect can vary wildly. A simple example of this comes from card games: some have mechanics where the player flips cards off the top of their deck until they flip a card that meets certain criteria, and then they do something with that card—oftentimes playing it for free. Without carefully restricting the scope of what that effect can ultimately let you play, you risk creating an extremely swingy scenario, where the outcome and benefit of the effect depend fully on the (usually) randomized deck. Similar things can be said about dice, but we’ll get to that in a minute.
Randomness isn’t the only cause of swingy effects. Another factor is also the cost of an effect, whether it’s a direct resource cost or other kind of investment. If some action costs a lot to take or requires that the player put themselves in a risky situation, only to then have the counterplay to that action cost a lot less (either in resources or opportunity cost), that action becomes swingy. The best case is you getting the full benefits from the expensive action and the worst case is either getting nothing or actively losing progress due to counterplay being trivial in comparison.
In cases like this, mitigating swinginess requires either the counterplay to get proportionally harder depending on the effect/action in question, or said effect/action to become more resistant to counterplay. One way this can be handled is for the effect to be partially immune to counterplay, so that the player gets at least something out of the large investment; for example, the extremely expensive Eldrazi creatures in MtG have part of their effect be extremely hard to interact with, so it’s not a complete waste of the resources you spent on them.
The last common avenue for swinginess comes in the form of scaling effects. Any kind of direct scaling, with linear scaling being the most common form. This is essentially any ‘do X damage, where X is <something>‘-style effect. Depending on the bounds of X for the effect (if any exist, that is), and whether that X comes from investing resources or something like counting specific things in play, there’s a potentially massive gap between the possible outcomes. However, as swingy as linear scaling can be, it’s often easy to set those bounds and to keep things under check.
Where it really gets hectic is when you mix scaling with randomness, i.e. usually dice scaling. Things like rolling a single die and adding the value to an effect needs very careful consideration of the numbers involved. For example, if the numbers in your game usually go between 1 and 20, and you roll a 12-sided die, even without adding the value to some baseline from the effect, the range of possible values is more than half the full range of values in your game. In something like an RPG, if this is how you handle things like dealing damage, it quickly becomes a case of luck if something is a glancing blow or a potential 2-hit kill. Now, the fortunate thing with dice is that this kind of swinginess only really exists with single-die setups, where each number on the die has an equal probability of occurring. Introducing multiple dice (of the same kind) changes this probability and provides a narrower band of possible outcomes, which is usually much easier to handle.
In conclusion, swinginess itself is swingy. Too much of it, and the game becomes either unpredictable or prone to blowouts that make it less interactive, and therefore less fun. Too little swinginess—or none at all—can make for stale gameplay, without any real ups and downs to the overall tension. Randomness is exciting. Swinginess is exciting. Don’t take either too far. Only a Sith deals in absolutes.